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By: Charles Apperson and Michael Waldvogel, Extension Entomology

Insect Note - ENT/rsc-6

Mosquitoes are important pests because their biting activity often interferes with outdoor activities and can transmit disease organisms to people and domestic animals. Most mosquitoes are active during twilight hours and at night; however, around the home, the mosquitoes that breed in discarded containers are active during the day. Mosquitoes need water to complete their life cycle. They can breed in almost any source of water. Pesticides are only a short-term solution to nuisance mosquito problems. Solving the problem effectively and safely requires:

  • Proper identification - knowing which mosquito species are in your areas.
  • Learning about the biology and behavior of these particular species.
  • Locating and eliminating breeding sites, particularly artificial sites that are often around your own backyard.
  • Using appropriate chemical controls measures, including personal protection.


line drawing of a typical mosquito life cycle

Mosquito Life Cycle

All mosquitoes need water to complete their life cycle (see diagram). Some mosquitoes lay their eggs either individually or in "rafts" on the surface of the water. These eggs usually hatch within 24-48 hours depending on water temperature. Other mosquitoes deposit individual eggs on the sides of treeholes or discarded containers, or in depressions in the ground that will hold water. These eggs surviive over the winter and can even lie dormant for several years. Some eggs hatch when they are flooded by rainfall. Several flooding and drying cycles may be needed for all of the eggs to hatch that are laid by a particular female mosquito. The hatching eggs release larvae that are commonly called "wrigglers" because you can often see the larvae wriggling up and down from the surface of the water. Generally, the larvae feed on microorganisms and organic material in the water, but some mosquitoes prey on the larvae of other mosquito species and are regarded to be beneficial. In about 7-10 days after eggs hatch, larvae change to the pupal or "tumbler" stage in preparation for adult life. Adult mosquitoes emerge in about 3-4 days and may feed first on plant nectar. Female mosquitoes begin searching for an animal on which to feed several days after emerging from water. Male mosquitoes mate with females one to two days after the females emerge. Males do not bite, but they do feed strictly on plant juices.

Mosquito Breeding Sites

Tree holes can fill with rain water and become mosquito breeding groundsSince mosquitoes need water to complete their life cycle, the source of a mosquito problem can be just about anywhere that water can collect. Farm ponds and lakes are typically not major mosquito breeding areas if they contain fish and are relatively free of weeds, algae or floating debris in which mosquito larvae can hide. Permanent natural bodies of water, such as swamps, usually contain a wide variety of predatory insects and fish that keep mosquitoes from reaching significant nuisance levels. Severe storms, such as hurricanes, may disrupt this system and allow mosquito populations to rise rapidly. In residential areas, human activities often create mosquito breeding sites or increase the production of mosquitoes in natural bodies of water. For example, road building and maintenance can create situations that impede the drainage of stormwater runoff, creating a mosquito breeding site. Clogged drainage ditches along roads can become productive mosquito breeding sites. Logging and construction activities often leave tire ruts and holes in the soil. These depressions are ideal breeding sites for "floodwater" mosquito species.



Some mosquito species, such as the Asian tiger mosquito, often fly short distances, but they may still be able to invade your property from surrounding areas in your neighborbood. Other species can fly several miles from their breeding sites. As a result, efforts by individuals to control mosquitoes on their property frequently have limited success. While pesticides are often seen as a solution to a mosquito problem, they are simply one small component of an integrated mosquito management approach.

Source reduction
A community-wide effort is needed to "clean up" and (preferably) eliminate mosquito breeding sites. Around your home and neighborhood, natural tree holes (seen at right) and man-made objects such as bird baths, boats, canoes, discarded tires, and plant pots collect rainwater and allow mosquitoes to breed literally right in our own backyard. Stagnant water in unused or poorly-maintained swimming pools becomes an ideal breeding site. This can be a particular problem on homes that are vacant (e.g., foreclosures). You can help reduce mosquito populations by eliminating or properly maintaining these problem spots:

  1. Containers such as this algae-filled tub attract mosquitoes"Tip and Toss" - empty or (preferably) get rid of containers, old tires, etc. that can hold stagnating water.
  2. If you use barrels/containers to collect rainwater for watering gardens, cover them with screening to keep out debris and mosquitoes. Keep the screens clear of debris as well.
  3. Dump excess water from dishers under outdoor flower pots.
  4. Flush the water out of bird baths at least twice weekly (the birds will appreciate the fresh water)..
  5. Store boats, canoes and other objects so that they do not collect rainwater. Remove water that collects in depressions in tarpaulins covering boats and other equipment or objects.
  6. Cover or drain unused swimming pools.
  7. Keep rain gutters free of leaves and other debris that prevent water from draining.
  8. Correct drainage problems in your yard that allow rainwater to pool in lowlying areas.
  9. Fill tree holes to keep them from being used as breeding sites by mosquitoes.
  10. Remove debris (or report drainage problems) in drainage ditches and culverts along private or public roadways.

Personal Protection - Repellants

Some personal protection from mosquitoes can be achieved through the use of insect repellents. Many of these products contain DEET (N,N-diethyl-m-toluamide), but the USEPA has updated its information on selecting repellent products. Select the desired formulation (e.g., lotion, aerosol spray or cream) containing the highest percent of active ingredient, as stated on the product label, and apply it to exposed skin. Repeated use of repellents over a short period of time is not recommended, especially for children and pregnant women. For additional information on repellent products, see the Insect Note ENT/rsc-5 - Insect Repellent Products

Candles containing oil of citronella are often used outdoors to repel mosquitoes from around decks and picnic tables. These products work best when there is relatively little air movement that might disperse tthe chemical too quickly.

Chemical Control
truck-mounted ULV sprayer applying insecticides for mosquito controlChemical control of mosquitoes primarily targets the adult. Some counties and municipalites may have mosquito control programs. Such wide area spraying should be based on surveying areas (rather than simply responding to complaints)
Outdoor backpack or hand-held foggers will keep mosquitoes away for several hours, but once the chemical dissipates, mosquitoes may return to the area. Spraying thickets or shrubs along the perimeter of your yard helps reduce the population of mosquitoes that rest in these areas. However, some species of mosquitoes may move readily back into these areas from surrounding untreated places. Consult the NC Agricultural Chemicals Manual or your county Cooperative Extension Center for more information on selecting appropriate pesticides for use against mosquitoes.

Think about Pesticide Safety
Whether applying pesticides yourself or hiring a professional service, please remember that insecticide can drift, i.e., can be carried by wind onto someone else's property. Regardless of the amount of chemical involved, "drift" and is actually illegal not matter how small of the quanity goes off-site. Before using chemicals on your property, you should take these precautions:

  1. If you're hiring a professional applicator, request a copy of the product label for the pesticide(s) that they will use. Some products advertised as "natural" or "the ingredient found in chrysanthemum flowers" are actually synthetic pesticides (called "pyrethroids") which are toxic to many insects including beneficial ones (lady beetles, honey bees and others) as well as to fish.
  2. Communicate with your neighbors about when and where you plan to treat your yard.
  3. Avoid spraying when bees and other pollinators are actively foraging (visiting flowers). Spray early in the morning or later in the evening.
  4. Before applying any pesticides in your yard (or having them applied for you) be sure that you look at what is on the other side of your fence, property line, or where you are spraying. Are there pets or children in the yard? Does your neighbor have any bee hives, a fish pond, or a vegetable garden? Many of the pesticides used to treat yards are not appropriate to be sprayed on edible plants.

    Insecticides are available for controlling larvae, but their application in either large bodies of water or small artificial breeding sites can be difficult and expensive, particularly for an individual homeowner. Control programs targeting mosquito larvae are best left to trained individuals in county or local government agencies. Most of these chemicals are not selective and some may even harm beneficial insects and other non-target organisms. Furthermore, use of these chemicals will provide only temporary reduction in mosquito populations. Modifying or eliminating breeding sites is the long-term solution to severe mosquito problems.

    Homeowners wanting to treat small areas, such as garden pools, etc, might want to try a bacterial insecticides that are available at many retail stores, garden centers and on-line garden suppliers. There are several products formulated as "donuts" ("dunks") or as granules that contain the bacterium Bacillus thuringiensis israelensis or "Bti". This bacterium kills mosquitoes, but does not harm fish, birds or other wildlife. The "dunk" versions are well-suited for small breeding sites (100 sq. ft. or less) and will control mosquito larvae for about 30 days. Before using Bti products, you need information on the life cycle and habitat requirements of mosquitoes in your area. Simply treating all areas of standing water without knowing if they are actually sources of the problem is a waste of time and money.

    Other Biological and Non-chemical Control Measures

  5. Install tight-fitting screens on doors and windows to help keep mosquitoes out of your home.
  6. Although bats and birds, such as Purple Martins, consume mosquitoes as part of their diet, but they do not have a significant impact on mosquito populations. You can install nesting boxes around your property to attract these natural predators to the area. However, bear in mind that the feeding activity of insect-eating bats and birds may not be sufficiently selective to cause noticeable reductions in mosquito populations. Also, many of our major mosquito problems occur when some predators are inactive (or less active). For example, the Asian tiger mosquito is most active during the daytime when bats are normally roosting.

  7. What Doesn't Work

    Electrocutor traps ("bug zappers") placed out of doors are not effective in reducing or eliminating mosquito populations. Studies have shown that less than ¼ of 1% of the insects "zapped" in such devices were actually biting insects. The majority of the insects killed in electrocutor traps are actually beneficial in some form. Electronic mosquito repellers that emit high frequency sound to "repel" mosquitoes have not been shown to be effective either.

    Several types mosquito traps that use radiant heat and/or chemicals such as carbon dioxide or octenol to attract mosquitoes are now being marketed in the U.S. To date, there are no scientifically-based studies that prove that these traps are able to provide control of local mosquito populations. Some mosquito species such as Asian tiger mosquito are not attracted to these particular chemical cues.

    Similarly, claims that certain plants placed around a porch or deck will repel mosquitoes are not supported by any scientifically-based test results.

Mosquito Species Identification

There are at least 60 species of mosquitoes found in North Carolina (Harrison, 2008 survey). Since the habitat requirements of mosquito species are known, proper identification of the mosquitoes can be used to obtain information on where to search for and identify likely breeding sites. Collect some mosquito specimens for identification. Adult mosquitoes attempting to land are easily collected by placing a small jar (such as a baby food jar) over them. If possible, collect several dozen specimens. Place the jar in a freezer overnight. Spread the mosquitoes between sheets of facial or toilet tissue to protect them from being damaged, then place them back in the jar. Take the specimens to your county Cooperative Extension Service Center where arrangements can be made to identify the specimens and provide you with the information you need on how to control your mosquito problem.

Asian tiger mosquito
Asian tiger mosquito

Picture courtesy of P. Koehler, University of Florida


Image of mosquito life cycle - Entomology Department, Purdue University

Pest information and control recommendations presented here were developed for North Carolina and may not be appropriate for other states or regions. Any recommendations for the use of chemicals are included solely as a convenience to the reader and do not imply that insecticides are necessarily the sole or most appropriate method of control. Any mention of brand names or listing of commercial products or services in the publication does not imply endorsements by North Carolina Cooperative Extension nor discrimination against similar products or services. All recommendations for pesticide use were legal at the time of publication, but the status of pesticide registrations and use patterns are subject to change by actions of state and federal regulatory agencies. Individuals who use chemicals are responsible for using these products according to the regulations in their state and to the guidelines on the product label. Before applying any chemical, always obtain current information about its use and read the product label carefully. For assistance, contact the Cooperative Extension Center in your county.

Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

Last updated - May 2016